Scoping study: Assessing the Impact of Feral Horses on Frost Hollow Communities

Prepared for the Australian Alps Liaison Committee
Michelle Dawson, April 2009

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Introduction

The Australian Alps national parks have biological, geological and geomorphological natural values of national and international significance (Coyne 2001). The Alps encompass relatively undisturbed, high altitude and high rainfall environments in a continent characterised by low lying, dry landscapes. They are the source of many rivers including the Murray, Murrumbidgee and Snowy, which sustain south-eastern Australia- with town and city water supply, with irrigation and with hydro-electricity. The values of the Australian Alps are threatened by climate change. Warmer temperatures and less precipitation will lead to loss of flora and fauna and ecosystem function and an increase in pest species (Maunsell Australia Pty Ltd 2008). Other major threats to the Australian Alps are feral animals and plants, fire and tourism (Coyne 2001). Pest animals are a major cause of biodiversity decline globally, and Australia has the unenviable record of having nearly half of the known mammalian extinctions worldwide. Eleven of Australia’s major introduced vertebrate pests (including feral horses) have economic, environmental and social costs of an estimated $720 million dollars a year (McLeod 2004).

Management of feral horses in the Australian Alps to date has been a difficult and complex issue because of the emotional and historical significance of horses. Resourcing research and management of feral horses has been identified as a high priority in the Australian Alps national parks (Coyne 2001). In spite of this, there is surprisingly limited research, even internationally, on feral horse impacts (Dawson et al. 2006). More peer reviewed research would illustrate the impact of feral horses in the Alps ecosystem, thus altering perceptions of whether horses belong in the Alps, increasing the perception of wild horses as a pest, and hence reducing the public controversy surrounding feral horse management (Nimmo and Miller 2007).

We are proposing a multi-faceted research program to evaluate the impact of feral horses on frost hollow communities (including bogs/fens, streams, wet heath and wet grasslands) in the Australian Alps. These communities have been targeted because 1) they are widespread, 2) they typically contain sphagnum bog communities, which are in decline, are endangered and are particularly susceptible to damage by horses 4 (Tolsma 2008 and references therein), 3) they play a vital role in the landscape storing and slowly releasing water, 4) they are biologically rich, and 5) horses preferentially use them (Dyring 1990).

It is envisaged that the proposed study would be conducted through a post-graduate research program with at least one doctoral student, and preferably more. The scale of the program would depend on funding. Ten to fifteen study sites (located across the ACT, NSW and Victoria) with a range in horse densities form very high to zero would be assessed. Initially a technique for measuring an index of horse density/activity needs to be developed at a scale relevant to the study. Then at each site attributes of the community would be quantified such as species richness and abundance, habitat quality, water quality, soil and bog condition and ecosystem function. The outcome of the project would be a demonstration of the impact feral horses have in the Alps, and the establishment of the relationship between feral horse density and the biotic integrity of frost hollow communities. These findings could then be used to set appropriate targets for feral horse management.